Multichannel signaling system



M. M. LEVY MULTICHANNEL SIGNALING SYSTEM Filed Oct. 21, 1948 j w I- July 4, 1950 MASTER OSCILLATOR SQUARE-WAVE GENERATOR FREQUENCY MULTlPLiER Patented July 4, 1950 g 2,513,947 I MULTICHANNEL SIGNALIN'G'SYSTEM' Maurice MoiseLevy; Earls Court, England; as-- signer to 'DheGeneml Elcctrie'-Company;..Lim

ited; London,1E-nglamT Application October 21, 1948; Serial Nb. 55,733 Iir GreatBritain August 14; 1946 The present-2 invention; relates tm distributors forexmnp'le;for.multirchannel;signalling:systems?.v telegraph systems anctiori'otherpurposes. Ito-is applicable for: example:- to: mult'r-channelii signail systems of the in. which each channek 5':-

is constitutedi by" a. train: of. pulses: modulated. inaccordance: with; intelligencez to: be? teansmittem, the: trains. of: pulses being: oi the: same recurrencefrequency andinterleaved: with. one another.

Thus in ezsystern; witln n channels- 1 the: pulsesv of:

each trainzaretusuallytime-delayed by;

According: to the" present: invention" as. distribi utor for: multi-channel signalling and other purposes comprises epcatho'de ray tube liaving'a=-plu-- ralityf of anodes, mean's for causing the cathode; ray to sweep over the anodesdn tum andimeans for applying: to an electrode of the tube an o'scil--- lation': which alternately: permits: and: substan tially prevents the; passage": of? electronsof J the? beam toithe' anodes; thefrequency and phaseeoff '1 the? oscillation. in. relations to the: shape; size andi dispositiom of. the" anodes and: the frequency and? phase off the: sweeping". movement: oi the" cathode: ray being such that: electrons-1 first reach. eacln anode: at; a: reg-ion away.- from: the; leading edge of a recurrence period relatively thaw puTseS of thereoft and are: substantially prevented from:

the preceding train. Modulation may for exam= ple be by width (i; e. durationof' pulse) or'time (1. es instant of occurrence of pulse)- either caseit is arranged that" eachpulse remains-withiir its allotted fraction oftherecurrenee period-L In"- otlier word's overlapping of'pul'sesof'one-channelwith those of" an adjacent" channel is avoided in v orderto-prevent-crosstalk;

In". systems of the liind set=fortlr it is necessary propriate channels; For." this purpose; what-L 3 as: as distributor: may BE? employedi One know-m form of: distributor is; ins. the: form: at a cathode ray tube: having; a: plurality of. anodes;- each: connected: with: a different channell- The cathode ray is; caused; by" siutabieiadeflectingi means to: sweep over the;- anndes in: turn; and to complete the traverse of? allthe: modes im the desired. pulse: recurrence. periodi- The required pulses are then. generated at the individual 40 anodes.

Withthis. known form of distributor the. shapes of the pulses generat'edl are dependent upon the shape of the spot produced by the". cathode rely upon the anodes and upon the shapes and elit positions'ofthe ano'destliemselves andiirisusual which usually involved high voltages, and a cane? fully; constructedzcathodesray tube;

Itvistheobject of thepresent invention to avoid the need for accurate beam, focusing and? tube-- signalling'andothen purposes;

reaching each anode-before thet beam'hasireachedt thestrailing edgeof: such anode wherebythe wave:

20" leadingand trailingiedges-ofzthe anodes-aiienizl'i'oseedges: at. which i the beam approaches and: leaves the; anodes. respectively;

The invention will'a be described byway; of; examplewith reference to the accompanying-r drawing in which Figure.- l is an diagrammatic; illustration: ozf-iv one" embodiment; suitable: foruse: in a multi-echannel signalling system;

Figure. 2 is a front elevation of. the anodes:- of:

0, thezdistributor. ofFigure. 1,

Figure13- shows a modification of. the: arranges: ment of Figure l employing two distributorsandi Figure: 4' shows a part; of:. an alternating form of. distributor according to 'the?iI1V&IItiOI1;

Referring; to Figures. 1. and 2; an. oscillation of rectangular waveform.- indieatedz at. [0 and: of a frequency 100.-kc:/s; is applied;tethe-controlgrid of; a, cathode? ray tube- M having ten; anodes l2 arranged symmetrically with respect to 'the-tube axisand: ina circle; Thecathode ray; beam: is. arrangedto be cut-ofi during the. negative; ha-lfl cycles of:- the oscillation and switched on during: therpositive-half: cycles of; the oscillation l0.. Two: sinusoidal deflecting; Currents" of the: waveform indicatedlat E3; of 10 kc./s. and: mutually phase displaced by are appliedto tw'ormutually penpendicular pairs of defiecting'coils. Wand I-E to serve-to deflect thev cathode. ray'ina:.circular track' over. theanodes;v

their phasemelation' andthepositions'of: the: coils" and anodes are such that when. the, beam; is: switched. on-by; each-positive-half-- cycle-of the 1 00;- kC./S. oscillation: it isin: a; position within. the: surface Ofi one of-: the anodes; and: that; before: it!

The: oscillations-- of. and 1.0? kC/Szx are derived: from a common: source: amt

leaves that surface it has been switched off by the negative half'cycle. The areas on the anodes which may be arranged to receive electrons are indicated at 30 in Figure 2.

In this way there is generated at each anode a pulse train having pulses of rectangular wave form defined bythe wave-form of the 100 kc./s. oscillation and a recurrence frequency of kc./s. The trains generated at three of the anodes l2 are indicated at I6, I? and I8. The "pulses of con-' secutive trains are spaced apart by .10 microsec onds.

It is desirable that the space between the positive half-cycles of the 100 kc./s. oscillation should be as great as possible and nevertheless it may be of such cross section as to produce a round spot desired to provide more channels than would be possible with the arrangement described. In this case, as shown in Figure 3, use may be made of two like cathode ray tubes I9 and 20. Assuming the same frequencies as have been described in connection with Figure l, a master oscillator 2! at 1(l'kc./s. serves tosynchronise a frequency multiplier and square wave generator 22 which furnishes oscillations l0 and H0 at 100 kc./s. The oscillations l0 and it are seen to be displaced in phase by 180 relatively to one another and they are fed respectively to the control grids of the two tubes i9 and 20. Sinusoidal oscillations from the master oscillator 2| are applied to the deflecting coils l4. I'5, l4, l5 of the two tubes as in the arrangement of Figure 1 and serve to cause the cathode rays to sweep over the two sets of anodes t2 and I2 in synchronism.

Each anode is associated with a different trans mission channel and channels which are consecuasassumed in the description of Figures 1 and 2, it may have a cross section which is somewhat elongated-in a radial direction with respect to its track. Moreover" it may be in the form of a double pencil each pencil having a circular or a I radially elongated cross section, and two contive in time are given consecutive reference numhers I, etc, for the tube is and 2, 4, 6 etc.

for the tube 20. Means may be provided for displacing the deflecting coils and the tubes with which they are respectively associated relatively to one another in order to adjust thephases.

So long as the phasing of the oscillations is and ID relatively to that of the deflecting currents and to the positions of the anodes is correctly adjusted within suitable limits (the adjustment is not critical), it will be evident that the waveform of the pulses at the anodes can be made independent of the shapes and dispositions of the anodes and the precise phasing of the beam rotation. The tubes l9 and 28 do not, therefore. require to be constructed with a high degree of accuracy.

The invention can be applied to a known form of electronic distributor described in Bell Technical Journal, April 1944, pages 190-202, in which a relatively long cathode is used and is surrounded by a number of electrodes or groups of electrodes.

The application of the invention to this type of tube will be described with reference to Figure4. A fiat beam of electrons 29 from the whole length of a cathode 23, which is elongated in a direc tion perpendicular to the plane of the paper, is

caused to rotate by means of a rotating magnetic Each group then constitutes centric rows (or two parallel lines) of anodes may 'be-provided to cooperate with the two pencils respectively.

With the arrangement so far described, the

said oscillation produces negative pulses upon the If desired posianodes as it sweeps over them. tive pulses .canibe produced by making use of secondary emission, from the anode, a suitable collecting electrode being'provided forthe secondary electrons and maintained at a suitably higher potential than theanodes. Such collecting electrode may be constituted by a conductive annular coating around the inner surface of the envelope of the cathode ray deviceand arranged I symmetrically with respect to all the anodes. The sec-ondary emission is, of course, arranged to exceed the primary electron current causing the secondary emission.

I claim: V l. A distributor comprising a cathode ray tube having a plurality-of spaced anodes, means 01 I sweepingthe cathode ray beamover said anodes in succession to generate electron current therein, an electrode for controlling the intensity of said beam, means for generating an oscillation 1 having a period equal to the time between successive engagements of said beam with a central region of successive ones of said anodes .and

means for applying said oscillation to said elecin succession togenerate electron current therein, each said anode having a leading edge on the side thereof at which said beam approaches the anode and a trailing edge of the side of the anode 'at which the beam leaves the anode and means'for switching said beam on and off at regions-"of each said anode situated between and away from said leading and trailing edges.

3. A distributor comprising a cathode ray tube having a plurality of spaced anodes, means for a sweeping the cathode ray beam over said anodes. in succession to generate electron current therein, anelectrode for controlling the intensity of said beam, means for generating an oscillation of substantially rectangular wave form and means to apply said'oscillation to said electrode to determine the waveform of each said electron cur- 1 rent.

4. A distributor comprising a cathode ray tube having a plurality of spaced anodes arranged around a circular-annulus, means for deflecting the cathode ray beam in a conical path to engage said anodes in succession and means for switching said beam on and ofl at regions of each anode away from edges thereof.

5. A distributor comprising a cathode ray tube having an elongated cathode and a plurality of anodes disposed substantially in a cylindrical surface surrounding said cathode and co-axial therewith, means for directing electrons in a fiat beam from said cathode to said anodes, means for rotating said beam about the axis of said cathode to engage said anodes successively and means for switching said beam on and 011 at regions of each anode away from edges thereof.

6. A distributor according to claim 5, wherein said switching means comprise a control electrode between said cathode and anode and means for applying oscillations to said control grid.

7. A distributor system comprising two cathode ray tubes, each having a plurality of spaced anodes and means for deflecting the cathode ray beam to engage the anodes of said tubes alternately, means for applying to one of said tubes an oscillation to switch the beam of said tube on and off, and means for applying to the other of said tubes an oscillation of substantially opposite phase to said first oscillation to switch the beam of the other of said tubes on and off, the beam in one tube being switched on when that in the other tube is switched off.

8. A distributor system comprising two cathode r y tub s, ea h havin a p r y o spaced 6 anodes and means for deflecting the cathode ray beam to engage the anodes of said tubes alternately, means for applying to one of said tubes an oscillation to switch the beam of said tube on and off at the regions of each anode away from edges thereof, and means for applying to the other of said tubes an oscillation of substantially opposite phase to said first oscillation to switch the beam of the other of said tubes on and off at the regions of each anode away from edges thereof, the beam in one tube being switched on when that in the other tube is switched off.

MAURICE MOISE LEVY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,977,398 Morrison Oct. 16, 1934 2,121,359 Luck et a1. June 21, 1938 2,178,074 Jakel et a1. Oct. 31,1939 2,186,388 Moritz, Jr. Jan. 9, 1940 2,241,809 De Forest May 13, 1941 2,265,848 Lewis Dec. 9, 1941 2,302,311 Goldsmith Nov. 17, 1942 2,426,208 Hardy Aug. 26, 1947 24 156 Whit ake D c. '1, 1.9443 

